common/docs/reference/stream/stream_router.md

stream_router

Property	Value
Kind	module
RTL source	rtl/stream/stream_cells.sv
Availability	Synthesizable RTL

Summary

Routes one valid/ready input to a selected output.

Functional Behavior

Routes one valid/ready input to a selected output. It follows the repository valid/ready rule: a payload transfers only when both signals are high in the same cycle, and a stalled valid payload remains stable.

Suitable Applications

Use for elastic pipelines, stream routing, arbitration, backpressure, and response handling.

Parameters

The declaration below is canonical; retain the RTL-enforced parameter range.

Parameter	Declaration
DATA_WIDTH	parameter int DATA_WIDTH = 32
PORTS	parameter int PORTS = 4
SELECT_WIDTH	parameter int SELECT_WIDTH = (PORTS > 1) ? $clog2(PORTS) : 1

Interface Definition

module stream_router #(
    parameter int DATA_WIDTH   = 32,
    parameter int PORTS        = 4,
    parameter int SELECT_WIDTH = (PORTS > 1) ? $clog2(PORTS) : 1
) (
    input  logic [SELECT_WIDTH-1:0]                 select_i,
    input  logic                                    in_valid_i,
    output logic                                    in_ready_o,
    input  logic [  DATA_WIDTH-1:0]                 in_data_i,
    output logic [       PORTS-1:0]                 out_valid_o,
    input  logic [       PORTS-1:0]                 out_ready_i,
    output logic [       PORTS-1:0][DATA_WIDTH-1:0] out_data_o
);

Port Summary

Signal	Direction	Declaration
select_i	input	input logic [SELECT_WIDTH-1:0] select_i
in_valid_i	input	input logic in_valid_i
in_ready_o	output	output logic in_ready_o
in_data_i	input	input logic [ DATA_WIDTH-1:0] in_data_i
out_valid_o	output	output logic [ PORTS-1:0] out_valid_o
out_ready_i	input	input logic [ PORTS-1:0] out_ready_i
out_data_o	output	output logic [ PORTS-1:0][DATA_WIDTH-1:0] out_data_o

Integration and Use

Observe vector sizing, selection encoding, and flush semantics in the declaration. Do not modify a valid payload while its corresponding ready is low.

stream_router #(
    .DATA_WIDTH(DATA_WIDTH),
    .PORTS(PORTS),
    .SELECT_WIDTH(SELECT_WIDTH)
) u_stream_router (
    .select_i(select_i),
    .in_valid_i(in_valid_i),
    .in_ready_o(in_ready_o),
    .in_data_i(in_data_i),
    .out_valid_o(out_valid_o),
    .out_ready_i(out_ready_i),
    .out_data_o(out_data_o)
);

Dependencies and Verification

The linked RTL source is the implementation authority and contains local assertions for unsupported parameter combinations. See docs/design.md for repository-wide CDC, reset, stream, and storage contracts, and docs/verification.md for the verification matrix.